A. Field of the Invention
The present invention relates generally to high pressure flow line connections or closures, and more particularly to high pressure flow line connections or closures which include a male member having a tapered annular exterior surface, a female member having a tapered annular interior surface, and a seal ring of generally trapezoidal cross-section positioned therebetween.
B. Description of the Prior Art
In the field of high pressure fluid handling, as for example in industrial heat exchangers, there have been developed a number of connection or closure arrangements for connecting together flow lines or conduits. One arrangement includes a male member, a female member, and a seal ring. The male member has an end with an inwardly tapered frusto-conical exterior surface. The female member has an end with an outwardly tapered frusto conical interior surface having an angle of taper with respect to the axis of the member that is less than the angle of taper of the end of the male portion. The seal ring is generally trapezoidal in cross-section and has an outer surface with an angle of taper substantially equal to that of the inner surface of the female member, and an inner surface having an angle of taper that is substantially equal to the angle of taper of the end of the male member. As the male and female members are urged into mating engagement, as, for example by flanges, the seal ring is wedged tightly therebetween.
A shortcoming of the trapezoidal seal ring connection of the prior art is in the difficulty encountered in properly seating the seal ring between the mating surfaces of the male and female members. If the seal ring is axially misaligned when the parts are put together, the seal ring will be subjected to uneven stresses as the male and female members are urged into tight mating engagement, which may cause the seal ring to fail by fracturing or curling. Additionally, if the seal ring is axially misaligned, but does not fracture or curl, the connection still may leak, which at extreme high pressures may be disastrous.
An improved connection or closure of the type described was developed in which the seal ring was formed to include a radially extending lip. The lip provided a visual indication of the proper alignment of the parts as the male and female members were urged into engagement. However, the prior lipped trapezoidal ring connections or closures were subject to failure because of improper size relationships between the male member, seal ring, and female member. During the tightening of the connection, the lip moves toward the female member. If the initial spacing between the lip and female member is too small, then during tightening, the lip and female member will contact and the lip may be sheared off or the forces exerted by the female member on the lip may cause the ring to fracture. If, on the other hand, the initial spacing between the lip and the female member is too great, then there may be insufficient surface contact between the seal ring and female member to provide an adequate seal.
An improved connection or closure including a seal ring having a radially outwardly extending lip is disclosed in copending U.S. patent application Ser. No. 411,498, filed Aug. 25, 1982, wherein the seal ring, male member, and female member are sized relative to each other such that an adequate seal is developed and the lip of the seal ring remains spacial apart from the end of the female member. However, in extreme high pressure uses, the required bolt tensions are so high that the lip still may be sheared off.
It is, therefore, an object of the present invention to provide a connection or closure that overcomes the shortcomings of the prior art. More specifically, it is an object of the present invention to provide a connection or closure arrangement wherein the combination of the male member, seal ring with a radially outwardly extending lip, and female member are sized relative to each other such that proper axial alignment among the parts is maintained and an adequate seal is achieved and the lip remains spaced apart from the end of the female member regardless of bolt tension.